An essential component of subterranean system maintenance is visual inspection. As such, the buried components of these systems are often located beneath tunnels or passages capped by manholes or other coverings to prevent access to the tunnels and passages and therefore to the systems themselves by unauthorized persons or animals. In the past, these tunnels or passages, hereinafter referred to as “risers”, were tubular shaped recesses formed from one or more segments of poured concrete. Likewise, poured concrete was often used to fashion the coverings, such as a lid or cover or cap, of the riser. However, use of concrete as the material for making risers can be expensive. Further, exposure to freeze-thaw and other natural forces over times periods of several years can cause the concrete to weaken and ultimately fail.
The durability, reduced weight, and decreased cost associated with plastics have enabled traditional concrete risers to be advantageously replaced with modern plastic ones. However, one drawback of the decreased weight associated with modern plastic risers is the concern that the lighter lids are more easily manipulated and removed by children and small animals. The danger that children and/or small animals might fall in and/or become trapped is a real concern with unsealed risers.
What is desired, therefore, is a secondary safety system for preventing entry into a riser in the event that the cap or lid of the riser becomes damaged and/or dislodged. Additionally, because riser sizes are not standardized and vary greatly in size, it is desired that a secondary safety system be capable of installation within a range of risers.